1. Technical Field
The present invention relates to a liquid ejecting head unit used in a liquid ejecting apparatus such as an ink jet recording apparatus and a liquid ejecting apparatus having the same, and particularly, to a liquid ejecting head unit capable of attaching a plurality of liquid ejecting heads with high precision and a liquid ejecting apparatus having the same.
2. Related Art
A liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting a liquid in the form of a liquid droplet and ejects various liquids from the liquid ejecting head. A representative example of the liquid ejecting apparatus includes an image recording apparatus such as an ink jet recording apparatus (a printer) that includes an ink jet recording head (hereinafter, referred to as a recording head) and performs a recording operation by ejecting a liquid-like ink from a nozzle of the recording head in the form of ink droplets. Further, in recent years, the liquid ejecting apparatus has been applied not only to image recording apparatuses, but also to various manufacturing apparatuses such as a display manufacturing apparatus.
Recently, a printer has been introduced which includes a single head unit configured by arranging and fixing a plurality of recording heads, each having a nozzle group with a plurality of nozzles arranged in parallel, to a head fixing member such as a sub-carriage (for example, refer to JP-A-2008-273109). The sub-carriage is a frame-like flat plate member of which a portion that is attached to the plurality of recording heads is opened, and is made of a synthetic resin for weight reduction. Each recording head is screw-fixed to the sub-carriage while being positioned with respect thereto.
However, a rotational moment generated when the recording head is firmly screw-fixed to the sub-carriage may be exerted on the sub-carriage, such that there is a possibility that the frame-like sub-carriage may be deformed. Particularly when the plurality of recording heads is sequentially attached to the sub-carriage, the sub-carriage may be further deformed to the degree to which recording heads are fixed since the rotational moment is exerted on the sub-carriage when each recording head is fixed thereto. Further, even when the recording head is attached and fixed through position adjustment, the sub-carriage is deformed by the rotational moment generated when the attached recording head is fixed, such that its position is deviated from its originally set position. Further, due to the accumulation of the deformation of the sub-carriage, the relative position between the recording heads, and further, the relative position between the nozzles of the recording heads are deviated. As a result, there is a concern that the image quality of a recorded image or the like may be degraded due to a deviation in the impact position of the ink with respect to a recording medium.
In order to prevent such problems, a technique may be considered in which the entire sub-carriage is made of a highly rigid material, for example, metal such as stainless steel or aluminum. However, in this case, the weight of the entire head unit increases. Corresponding to this increase in weight, in printers equipped with the head unit, there is a need to further increase the size of the motor for moving the head in order to move the head unit smoothly. As a result, there are problems in that the entire printer increases in size and due to this the cost thereof increases.
Furthermore, these problems are present not only in ink jet recording apparatuses equipped with the recording head ejecting ink, but also other liquid ejecting head units adopting a configuration in which a plurality of liquid ejecting heads is fixed to a frame-like head fixing member such as a sub-carriage and a liquid ejecting apparatus including the same.